A particularly lethal asbestos

Penetrating: The type of asbestos inhaled in Libby, Mont., consists of long, thin fibers that the body's defense mechanisms can't repel.

February 09, 2005|By Jonathan Bor | Jonathan Bor,SUN STAFF

The asbestos inhaled by residents of Libby, Mont., was never good for much - not for strengthening concrete, soundproofing buildings or insulating boilers, brake pads or clutches.

But if someone were to design an asbestos fiber that stood a good chance of triggering cancers and respiratory disorders, experts say, he could hardly have done better.

Nature made six types of asbestos, magnesium silicates that exist in nature as bundles of tiny fibers that can fray or be picked apart. The kind that occurred in the W.R. Grace & Co. vermiculite mine is known as tremolite, but not all tremolite is created equal.

Dr. Victor L. Roggli, a Duke University pathologist who studies asbestos-related illnesses, said Libby's tremolite was distinguished by its long, slender fibers, which make it particularly dangerous.

"The thinness of the fiber is important for it to be able to penetrate deep into the lungs, the lining of the lung and even the abdominal cavity," said Roggli, co-editor of Pathology of Asbestos-Associated Diseases.

"And the length is important, too. There are a number of studies showing that the body's defense mechanism can't get rid of long fibers. Once they are stuck in the lungs, they are stuck for a long time, decades."

Miners weren't the only ones who developed asbestos-related problems, according to the Justice Department, which obtained indictments against the company and seven people.

Seventy percent of those afflicted never worked in the mine but might have been exposed by breathing the thick dust that settled over the town and came home in workers' clothing.

Asbestos can cause ailments including mesothelioma, a lethal tumor of the lining of the chest and abdominal cavities; asbestosis, a widespread scarring of the lungs; and lung cancer.

"Typically, asbestosis takes decades of exposure at pretty high levels [among people] working with asbestos," said Roggli. In contrast, mesothelioma can be triggered by short-term contact, and though it is very rare, it is generally incurable.

Though asbestos is most dangerous in mines and indoor environments, where it can deliver a concentrated dose to the lungs, it occasionally causes problems outdoors.

Roggli said he diagnosed lung cancer and scarring in a man who had played on a pile of tremolite tailings as a child outside a vermiculite-processing plant in Minnesota. The man died at age 42, two decades after he had last played on the tailings.

Gayla Benefield, a community activist in Libby, said a few people in the town have mesothelioma and that a far greater number have scarred, thickened lungs. Benefield said she lost her father to asbestosis and a brother-in-law to mesothelioma. She has scarred lungs.

Though tremolite tends to occur alongside vermiculite in natural formations, it isn't always hazardous. At a vermiculite mine in South Carolina, tremolite of the short, stubby variety has posed little hazard, Roggli said.

Working in shipyards left a legacy of lung disease for thousands who toiled in the confined spaces of engines and boiler rooms. Most were exposed to amosite, a straight, splintery asbestos used in building materials.

A bluish asbestos, crocidolite, was widely used to reinforce concrete. It, too, can be harmful if inhaled but has caused far less disease because fewer people were exposed to it, Roggli said.

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